I think it's coming from both places, it's just that the top-down exhortations are so loud and insistent.

I wasn't around to experience it but my understanding is that this is what happened in the 90's with object oriented programming - it was a legitimately useful idea that had some real grassroots traction and good uses, but it got sold to non-technical leadership as a silver bullet for productivity through reuse.

The problem then, as it is now, is that developer productivity is hard to measure, so if management gets sold on something that's "guaranteed" to boost it, it becomes a mandate and a proxy measure.